I would like to join others in asking for a more up-to-date central documentation.
I'm fully aware it takes a lot of effort to make and keep documentation up to date, however going through the current outdated PDF documentation to only find it's not there and then having to go through the forum is not efficient, to say the least.
I started using NetXMS because it had the right features with a really useful GUI AND it had documentation. I'm using it because it's a wonderful product with support that some other commercial companies can only envy but I find myself loosing valuable time each time I need to add something to it because of lacking documentation. I really believe good documentation will help others discover and adopt this product.

I think wiki could be the right way to go. It's made for the purpose of knowledge share and the community can even help maintain and enhance it.
For those who prefer off-line documentation, tools exist to save it to an offline format.

Regards,

Dan